Security vendor FireEye has released a set of tools to analyze Poison Ivy infections

A malicious software tool perhaps most famously used to hack RSA's SecurID infrastructure is still being used in targeted attacks, according to security vendor FireEye.

Poison Ivy is a remote access trojan (RAT) that was released eight years ago but is still favored by some hackers, FireEye wrote in a new report released Wednesday. It has a familiar Windows interface, is easy to use and can log keystrokes, steal files and passwords.

Since Poison Ivy is still so widely used, FireEye said it is harder for security analysts to link its use to a specific hacking group.

For its analysis, the company collected 194 samples of Poison Ivy used in attacks dating to 2008, looking at the passwords used by the attackers to access the RATs and the command-and-control servers used.

Three groups, one of which appears to be based in China, have been using Poison Ivy in targeted attacks going back at least four years. FireEye identified the groups by the passwords they use to access the Poison Ivy RAT they've placed on a target's computer: admin338, th3bug and menuPass.

The group admin388 is believed to have been active as early as January 2008, targeting ISPs, telecoms companies, government organizations and the defense sector, FireEye wrote.

Victims are usually targeted by that group with spear-phishing emails, which contain a malicious Microsoft Word or PDF attachment with the Poison Ivy code. The emails are in English but use a Chinese character set in the email message body.

Poison Ivy's presence may indicate a more discerning interest by an attacker, since it must be controlled manually in real-time.

"RATs are much more personal and may indicate that you are dealing with a dedicated threat actor that is interested in your organization specifically," FireEye wrote.

To help organizations detect Poison Ivy, FireEye released "Calamine," a set of two tools designed to decode its encryption and figure out what it is stealing.

Stolen information is encrypted by Poison Ivy using the Camellia cipher with a 256-bit key before it is sent to a remote server, FireEye wrote. The encryption key is derived from the password the attacker uses to unlock Poison Ivy.

Many of the attackers simply use the default password, "admin." But if the password has changed, one of Calamine's tools, the PyCommand script, can be used to intercept it. A second Calamine tool can then decrypt Poison Ivy's network traffic, which can give an indication of what the attacker has been doing.

"Calamine may not stop determined attackers that use Poison Ivy," FireEye warned. "But it can make their criminal endeavors that much more difficult."